The present invention relates generally to a radar sensor cover and, more specifically, to a sensor cover that allows minimal radar signal attenuation and minimal radiation pattern distortion.
The use of high frequency sensors in automotive detection and control systems is becoming more prevalent. One type of high frequency sensor frequently used in vehicular applications is a radar sensor. For example, adaptive cruise control (ACC) systems utilize a radar sensor to control the speed and distance of a vehicle equipped with an ACC system and a target vehicle. For aesthetic purposes, it is advantageous to hide the sensor components from view. However, the customary materials that are used for exterior vehicular shells, namely metals, are not transparent to the high frequency waves, including radar waves.
There are several prior art cover designs that are used to hide or camouflage the sensor components. One known cover design is made from an opaque non-metallic material that is essentially transparent to high frequency signals. A disadvantage of this type of cover is that the cover does not contain any metal and therefore does not blend in with the body of the vehicle.
Another known sensor cover design includes a very thin planar layer of metal. Such a structure is disclosed in U.S. Pat. No. 6,184,842 B1. The sensor cover in this disclosure includes a covering member formed of a radar-transparent material, an area formed on the surface of the radar-transparent material in the shape of a selected characteristic structure or symbol, a visible metallic or metallically glossy layer on the structure or symbol where the thickness of the metallic or metallically glossy layer is such that electromagnetic radiation of the radar system penetrates it substantially without attenuation. A disadvantage of this type of system is that the metallic area must be minimal to obtain minimal signal attenuation.
Thus, there is a need for metallic sensor covers that allow for a large metallic area and that provide minimal sensor signal attenuation. This invention provides such an improved/new and useful sensor cover.
The present invention overcomes the disadvantages described above of known sensor covers. An aspect of this invention is to form a high frequency electromagnetic wave transparent cover that can be designed as a decorative structure, such as a logo or manufacturer nameplate, or as any vehicle component, such as a grill. The cover is therefore aesthetically pleasing, while also providing the advantage of allowing transmission of high frequency electromagnetic waves, including radar waves, with minimal interference. This invention will disclose several constructions that have a metallic appearance from an elevational view, but allow high frequency wave transmission.
The present invention provides a sensor cover for camouflaging a high frequency electromagnetic wave transmitting sensor. The sensor cover includes a substrate having a non-planar surface wherein the surface has non-signal transmitting regions and signal transmitting regions. Each of the non-signal transmitting regions is separated by at least one of the signal transmitting regions. A metallic layer is disposed on each of the non-signal transmitting regions of the substrate.
The distance between the metal adhered non-signal transmitting regions and the repeat pattern of the metal adhered non-signal transmitting regions provide the visual appearance of a solid metal layer while allowing minimal attenuation and minimal radiation pattern or beam distortion of the sensor signal. The cover of the present invention may be used with a high frequency sensor is capable of both transmitting and receiving signals.
In another aspect of the present invention a method of constructing a sensor cover for camouflaging a high frequency sensor is provided. The method includes the steps of: A) forming a substrate having a non-planar surface, where the non-planar surface includes non-signal transmitting regions separated by signal transmitting regions; and B) adhering a metal layer on each of the non-signal transmitting regions of the substrate.